Apparatus for making espresso coffee

ABSTRACT

An apparatus for making espresso coffee is described. The apparatus comprises a support frame ( 2 ) upon which an open-topped cylinder ( 3 ) is vertically mounted. A pot containing a quantity of ground coffee may be attached to the base of the cylinder, and the frame ( 2 ) and cylinder ( 3 ) provide sufficient space to insert a cup or cups below the pot. A piston with a piston head ( 22 ) is adapted to fit in the cylinder ( 3 ) and a pair of levers ( 6, 7 ) pivoted to the frame and pivotally linked to the piston enable the piston head to move up and down in the cylinder ( 3 ) by actuation of the levers ( 6, 7 ). In use, hot water is poured into the cylinder ( 3 ) and downward pressure on the levers ( 6, 7 ) expels the hot water under pressure through the ground coffee and the freshly made coffee passes out of an outlet in the base of the pot and into a waiting cup.

This invention relates to apparatus for making espresso coffee.

Coffee is globally one of the world's most widely consumed beverages. Itis normally drunk hot and it is made by extracting soluble componentsusing hot water from so-called ground coffee, i.e. a granular powderformed by grinding roasted coffee beans. It is well-known that the tasteof the coffee varies substantially, even with identical ground coffee asthe starting material, depending upon the precise conditions under whichthe extraction is carried out. One known widely used method is to pass arelatively small quantity of hot water through a compacted block ofcoffee grounds under relatively high pressure in order to force thewater through the block. This results in a quantity of so-calledespresso coffee which is the type of coffee beverage preferred by manyusers.

In order to produce espresso coffee, e.g. in a café or restaurant, it iscommon to use for this purpose a counter-top size so-called “espressomachine”. These machines are generally provided with a plumbed-in watersupply and include means for maintaining a reservoir of water at arelatively high temperature as well as complex systems for expelling ameasured quantity of that hot water via a block of compressed groundcoffee. That block is held tightly against a pressurised water outlet ofthe machine by means of a cylindrical metal pot in which the block iscompressed. The block may be of loose coffee granules put into the pot(conventionally it is filled to the brim, the granules then beingcompressed to a smaller volume when the pot is affixed to the machine),or may be in the form of a sachet or ‘pod’ made of water-permeablematerial and sized to fit snugly into the pot. The pot is provided withmeans to hold it sealed tightly against the pressurised water outlet.Conventionally this is achieved by projections on the exterior of thepot engaging short thread portions on the interior of a skirtsurrounding the outlet. The pot is usually provided with a laterallyextending exterior handle enabling the pot to be screwed tightly intoposition by turning through around 90°. The base of the pot contains anaperture through which the coffee may pass to drop into a cup placedbelow the pot during dispensing, which may be bifurcated to divide theoutflow into two streams each of which then drops into a cup placedbelow the pot.

Apparatus of this sort provided for café and restaurant use is ofsubstantial size and usually requires plumbing into a water system andis accordingly not ideally suited for domestic use. An example of suchapparatus is described in U.S. Pat. No. 4,421,014. Scaled down suchapparatus for domestic use has been manufactured for many years, butsuch apparatus has conventionally required an electrical supply and hasincorporated suitable means for generating hot water under pressure andexpelling a quantity of it through the pot containing the compressedblock of coffee grounds. Other attempts to make an apparatus suitablefor domestic use are shown in U.S. Pat. No. 4,763,566 and GB-A-801,609.A simpler design is described in FR-A-728,361 where a cylindercontaining a piston, actuated by a pair of levers, is used to forcewater through a grille upon which coffee grounds are located.

We have now found that, by careful design, it is possible to produceexcellent espresso coffee using apparatus that is simple in operation,requires no electricity supply or permanent plumbing, and which can beproduced in quantity relatively inexpensively, thus further extendingthe market for domestic espresso coffee-making apparatus.

According to the present invention, there is provided apparatus formaking espresso coffee comprising a support frame, a vertically mountedopen-topped cylinder mounted on the support frame, the frame andcylinder defining a space below the cylinder adapted to recieve a blockof compressed ground coffee and below which a cup to receive the coffeemay be inserted, means for locating adjacent the base of the cylinder aquantity of ground coffee, a piston adapted to fit in the cylinder, andan actuation means linked to the piston enabling the piston to be movedup and down in the cylinder by the actuation means, wherein associatedwith the piston is a means for enabling water to pass the head of thepiston as the piston is raised within the cylinder by the actuationmeans.

A variety of actuation means can be envisaged, for example, mutuallyengaging throughthreads on a piston shaft and on a bore located at thetop of the cylinder through which the shaft extends. Alternatively,pneumatic pressure such as with an inflation bag could be used toactuate the piston.

The preferred actuation means are a pair of levers pivoted to the frameand pivotally linked to the piston. Such levers may be geared togetherto promote even pivotal movement thereof.

Preferably the levers are mounted 180° apart relative to the axis of thecylinder and movable from an elevated position in which the piston islocated at or near the top of the cylinder to a lowered position inwhich the piston abuts the base of the cylinder.

The most convenient way of locating the compressed granules adjacent thebase of the cylinder is to use a standard pot, e.g. bayonet fitted tothe support frame, though the apparatus may be configured with asuitable sachet or ‘pod’ receptacle instead, e.g. hingeable down toenable insertion of a fresh sachetpod and swivellable up and clippablein position to hold the sachet/pod compressed against the underside ofthe cylinder.

To use the preferred form of such apparatus, the user first places aquantity of ground coffee in a pot which may be one of the standardconventional designs with one or more outlets to direct coffee into oneor more cups. The pot is then fitted underneath the cylinder inconventional fashion and the desired number of cups are placed beneathit. The cylinder is then filled with hot water and the hot water thenexpressed from the cylinder by means of the piston actuated by movingthe two levers. The movement of the levers is under the control of theuser and can be controlled accordingly to expel the hot water from thecylinder through the block of compressed ground coffee relatively slowlyat a relatively low pressure, or relatively fast at a considerablyhigher pressure. The taste of the resulting coffee differs andaccordingly the user can operate the apparatus to suit his or her taste.

In operation, as noted above, the cylinder is first filled to thedesired extent with hot water above the piston. The piston is thenraised and the water passes the piston head to collect in the lowerregion of the cylinder, e.g. via a one-way valve mechanism mounted inthe piston. Such a valve should be easy to operate, easy to clean, andcapable of withstanding the substantial back pressure exerted as the hotwater in the cylinder is expelled under pressure through the compressedblock of ground coffee.

In a particularly preferred embodiment, this valve mechanism is providedby constructing the piston with an axially movable seal ring locatedbetween the exterior periphery of the piston and the internalcylindrical wall of the cylinder, the seal ring being held captivebetween a pair of axially spaced flanges on the piston, the axialspacing between the flanges exceeding the axial dimension of the sealring, and the arrangement being such that when the seal ring is adjacentthe lower flange of the piston, flow channels formed in the piston areopen and wherein those flow channels are closed when the seal ring isadjacent the upper flange.

It is found that this is a particularly simple and effective way ofproviding a valve in the piston, particularly when the seal ring is aresilient o-ring compressed between the exterior of the piston and theinterior wall of the cylinder. As the piston is raised within thecylinder, the o-ring rolls to lie adjacent the lower flange opening theflow channels and enabling water above the cylinder to flow through theminto the increasing volume between the end of the cylinder and therising piston. When the piston is moved downwards, the ring rolls to lieadjacent the upper flange and to seal the exterior periphery of thepiston tightly against the internal cylindrical wall of the cylinder,thus allowing the application of pressure to the water in the cylinderto express it through the compressed block of ground coffee.

Preferably the linkage between the piston and the levers or otheractuation mechanism is easily and quickly dismountable so that thepiston may be removed entirely from the cylinder to enable it to becleaned. The cylinder may also be easily dismounted from the supportframe, for like purposes.

Other features and advantages of the invention will become clear fromthe explanation of a particular preferred embodiment of apparatusaccording to the invention which is shown by way of example in theaccompanying drawings. In those drawings:

FIG. 1 is a perspective view of apparatus for making espresso coffee inaccordance with the present invention,

FIG. 2 is an exploded view of the apparatus of FIG. 1 showing thevarious components thereof,

FIG. 3 is a perspective view of the piston of the apparatus of FIG. 1inverted, and

FIG. 4 is a longitudinal section through the centre of the piston.

Referring to the drawings, the apparatus consists generally of a baseplate 1 on which is mounted a main body portion 2 in the form ofgenerally arched shape having two downward legs attached to either endof the generally oval base plate 1 and having at its upper end acylindrical collar 4 into which is fitted an upwardly open cylinder 3.Mounted to the collar 4 are two actuation levers 6, 7, each of whichconsists as shown in the drawing of an arm which bifurcates into twoshorter arms, each shorter arm having an aperture 8 near its free end.The free ends of the shorter arms of levers 6, 7 are relieved to receiveone of four apertured plates 11, 13 each of which has an arcuate toothededge. Each plate 11, 13 is held adjacent the facing ends of the shorterarms by a collet 31, which collets can be assembled to the arms andplates straightforwardly, whereafter the ends of the levers 8 carryingplates 11, 13 and collets 31, can be slipped over four cylindrical posts10 on the collar 4, bringing apertures 8 into line with apertures ineach post 10. The toothed plates 11, 13 and the levers 6, 7 are heldcaptive and pivoted on to collar 4 by means of four fixing screws 12which pass through apertures 8 and into posts 10, with each plate 13then meshing with a plate 11, so linking the pivotal movement of levers6 and 7 together.

Adjacent the bifurcation in each of levers 6 and 7 is a slot 15 which isadapted to receive one end of a linkage arm 16. Each of the twoidentically shaped arms 16 is held pivoted in slot 15 by virtue of a pin(not shown in the drawings) which passes through a transverse bore 18 ineach of levers 6 and 7 and a hole 19 at the lower end of each arm 16,and two spacer washers 32 either side of hole 19.

The upper ends of arms 16 are cut away to one side, the remainder beingpivotally connected with the upper end of a plunger assembly generallydenoted 21 in FIG. 1. The plunger assembly is shown in more detail inFIGS. 3 and 4 and consists of a moulded piston consisting of a head 22and an upwardly extending plate 23 moulded integrally therewith. Theupper end of plate 23 has a bore 25 through which a threaded stud 26 andcollar 28 may pass, in order to form the pivotal connection with theupper ends of arms 16, one side of each arm lying against each side ofplate 23.

When the apparatus is assembled as shown in FIG. 1, it can beappreciated that, when the levers 6 and 7 are raised, raising in an evenfashion being achieved by the meshing of toothed plates 11, 13, assembly21 is raised so that the piston head 22 lies adjacent to the top ofcylinder 3. By moving levers 6 and 7 downwards, towards the positionwhere they lie against the legs of main body portion 2, the plungerassembly 21 is moved downwards in the cylinder 3.

Piston head 22 is sized so as to enable it to be easily moved up anddown in cylinder 3, by moving the levers 6 and 7. In order to seal theoutside of the piston head 22 to the interior wall of the cylinder 3,the piston head 22 bears an external o-ring which is shown in thedrawings only in FIG. 2. The o-ring, denoted 40, may adopt a positionadjacent a lower flange 41 moulded on the exterior periphery of thepiston head 22, or a position in which it lies against an upper flange42, likewise integrally moulded. When the piston is being pulled upinside the cylinder 3, o-ring 40 moves to lie adjacent lower flange 41.When the piston is moved down inside cylinder 3, the o-ring 40 rolls tolie against upper flange 42.

As shown most clearly in FIG. 3, the lower portion of the piston head 22(shown uppermost in FIG. 3 where assembly 21 is shown inverted) is inthe form of a hollow skirt with internal radial reinforcing ribs 45.Around the periphery of the skirt are six apertures 47 which extend fromadjacent lower flange 41 to approximately half-way up the space betweenflanges 41 and 42.

When the o-ring 40 is adjacent lower flange 41, there are spacesaccordingly enabling water to pass between the side of the piston andthe wall of cylinder 3 through apertures 47 and into the space belowpiston head 22. When the piston is lowered, however, o-ring 40 moves tolie against upper flange 42, thus constituting a complete seal aroundthe entire periphery of the piston head 22, so enabling water to beexpressed under pressure from cylinder 3. In order to assist the flow ofwater downwardly past the piston head 22 as it is raised within cylinder3, the upper edge of the piston head 22 is relieved by a set of notches49.

As shown in the exploded diagram in FIG. 2, the base of cylinder 3 haslocking formations 14 thereon which are adapted to engage in abayonet-fitting fashion with a number of projections located internallyof collar 4 so that cylinder 3 may be held fast against axial movementin collar 4, but, for example may be easily removed for cleaning.

In order to maintain a good seal, an o-ring 9 is located between thebase of cylinder 3 and the upper face of a rubber perforated diaphragm50. The diaphragm 50 is held in place by a locking ring 52 held in placeby bolts passing through four lugs and screwed upwardly into sockets incollar 4. Ring 52 which has two cutouts at the ends of two internalspiral ramp sections 54, constituting, with the conventional projectionson the side of a standard pot, a bayonet-type connection. The rubberperforated diaphragm 50 acts as a seal between the base of cylinder 3and the upper edge of a conventional handled pot for containing aportion of ground coffee. The pot may be swivelled to rotate the potabout its axis in a first direction such that the standard projectionson the exterior of the pot engage the spiral ramp sections 53. Thisbrings the upper edge of the pot into contact with the lower face ofdiaphragm 50 and accordingly seals the cylinder 3 against the pot. Thepot may easily be removed by rotating it about its axis, in the oppositedirection, until the projections disengage with the ramp sections 54 sofreeing the pot and enabling used coffee grounds to be discarded. Inaddition, the diaphragm 50 also serves to prevent coffee grounds beingsucked from the pot into the bottom of the cylinder 3 by the backpressure exerted as the apparatus is used.

Finally, base 1 has an external rim 70 to contain any spillage and onits floor a series of raised coffee bean shaped formations 71 whichserve to hold a cup placed on base 1 out of contact with the upper sideof base 1 and accordingly unlikely to pick up any liquid which may havedropped on to the base during use of the apparatus.

Use of the apparatus is straightforward:

First of all, a pot is filled with ground coffee either loose or in asachet or ‘pod’ and fitted into place in conventional fashion by liftingand twisting. At this stage, the levers 6 and 7 are in their downwardposition, as shown in FIG. 1, and the piston head 22 is adjacent thebase of cylinder 3. Hot water is now poured into the top of cylinder 3,for example from a conventional electric kettle. The cylinder is thenfilled to the desired degree. It need not be filled fully if the userdesires a smaller cup of coffee than the is capacity of cylinder 3 andthe side of the piston may bear markings if desired to assist in acuratefilling, e.g. a line corresponding to a quantity of water equivalent toa standard ‘single’ espresso, and a second, higher line for a ‘doubleespresso’ quantity. The levers 6 and 7 are then moved upwards. Via arms16, this raises the plunger assembly 21 and because, as the movementstarts, o-ring 40 moves to the position adjacent the lower flange 41,the water now flows from above the piston head 22 to below it. This isachieved simply and effectively and the apparatus is then in a positionwith the levers 6, 7 elevated and with the piston head 22 located at ornear the top of the cylinder 3. From that position, levers 6 and 7 arepressed downwards and, at the start of that motion, communicated viaarms 16 to the plunger assembly 21, o-ring 40 shifts to the positionadjacent upper flange 42, thus sealing the piston head 22 against theinterior wall of cylinder 3 and now enabling the water to be expelledunder pressure from cylinder 3 by continued downward pressure on levers6 and 7. Provided that the coffee grounds are tightly packed and theseal using diaphragm 50 is well-made, quite substantial pressure isrequired on the arms which translates into a substantial water pressureabove the compacted grounds. The meshing of toothed plates 11, 13provides gearing on the levers 6 and 7 so evening up the forces appliedto the arms to provide the substantial water pressure. The freshly-madecoffee emerges from the compacted grounds in the pot and emergesunderneath the pot to drop into a waiting cup.

To make another cup, the handled pot is swivelled to release it, theused grounds removed, fresh grounds inserted and the process repeated.It is quick, simple, elegant and makes an excellent cup of espressocoffee.

1. An apparatus for making espresso coffee comprising a support frame (2), a vertically mounted open-topped cylinder (3) mounted on the support frame, the frame and cylinder defining a space below the cylinder adapted to recieve a block of compressed ground coffee and below which a cup to receive the coffee may be inserted, means for locating adjacent the base of the cylinder a quantity of ground coffee, a piston adapted to fit in the cylinder, and an actuation means linked to the piston enabling the piston to be moved up and down in the cylinder by the actuation means, wherein associated with the piston is a one-way valve mechanism for enabling water to pass from above to below the head (22) of the piston as the piston is raised within the cylinder by the actuation means.
 2. An apparatus for making espresso coffee according to claim 1 wherein the actuation means are a pair of levers (6, 7) pivoted to the frame and pivotally linked to the piston.
 3. An apparatus for making espresso coffee according to claim 2 wherein the levers (6, 7) are mounted 180° apart relative to the axis of the cylinder (3) and movable from an elevated position In which the piston is located at or near the top of the cylinder to a lowered position in which the piston abuts the base of the cylinder.
 4. An apparatus-for making espresso coffee according to claim 2 or 3 wherein the linkage (16, 29, 30) between the piston and the levers (6, 7) is easily and quickly dismountable so that the piston may be removed entirely from the cylinder (3) to enable it to be cleaned.
 5. An apparatus for making espresso coffee according to any of claims 2 to 4 wherein the levers (6, 7) are geared together to promote even pivotal movement thereof.
 6. An apparatus for making espresso coffee according to any one of claims 1 to 5 wherein the one-way valve mechanism for enabling water to pass the head (22) of the piston is an axially movable seal ring (40) located between the exterior periphery of the piston and the internal cylindrical wall of the cylinder (3), the seal ring being held captive between a pair of axially spaced flanges (41, 42) on the piston, the axial spacing between the flanges exceeding the axial dimension of the seal ring, and the arrangement being such that when the seal ring is adjacent the lower flange (41) on the piston, flow channels (47) formed therein are open and wherein those flow channels are closed when the seal ring is adjacent the upper flange (42).
 7. An apparatus for making espresso coffee according to claim 6 wherein the seal ring (40) is a resilient o-ring compressed between the exterior of the piston head (22) and the interior wall of the cylinder.
 8. An apparatus for making espresso coffee according to any of claims 1 to 7 wherein the cylinder (3) is mounted in the support frame (2) by way of a bayonet-type fitting (14).
 9. An apparatus for making espresso coffee according to any of claims 1 to 8 wherein the support frame (2) is provided with a base (1) containing raised formations (71) on its upper surface such that a cup placed on the base rests on the raised formations and out of contact with the upper surface of the base.
 10. An apparatus for making espresso coffee according claim 9 wherein the base (1) is provided with an external rim to contain spillage,
 11. An apparatus for making espresso coffee according to any of claims 1 to 10 wherein the means for locating a quantity of ground coffee at the base of the cylinder comprises a standard pot adapted to contain a quantity of couffee grounds, and, on the pot and at the base of the cylinder, interengagable means enabling the pot to be held against the base of the cylinder with the grounds compressed therein. 